#define _CRT_SECURE_NO_WARNINGS 1
#include<stdio.h>
//实现求n的阶乘
int main()
{
	int i = 0,j,s=1;
	scanf("%d", &i);
	for (j = 1; j <= i; j++)
	{
		s *= j;
	}
	printf("%d", s);
	
	return 0;
}